Over the course of its last two albums, Low has been investigating methods by which to expand its sound, a pretty natural progression for any group of artists working their way up to LP number six and virtually imperative for a band with an infrastructure as skeletal as theirs. You can walk across arctic tundra for only so long before the permafrost yields to tillable soil. And while its formula hasn't deviated all that much from the first album, its sixth, Trust, is light-years away from the ice field of 1994's I Could Live in Hope and even from 1999's blissful Secret Name. Low is still writing allegorical and vaguely religious songs, but the forms have evolved, ranging from the thumping fuzz of "Canada" to the banjo-inflected soft rock of "In the Drugs." That Low invited Gerry Beckley of America to contribute vocals is interesting only as a passing tidbit; of more importance is Tchad Blake's addition of breadth and depth to the final mix. Stray piano notes plink, patch cords crackle, and a host of creepy ambient sounds proliferates on the album, gurgling underneath the familiar vocals of Alan Sparhawk and Mimi Parker. But the most convincing moments on the record come from a wiry quartet of songs that quivers like a bundle of raw nerves, bristling with anticipation and tension even when Sparhawk is very nearly screaming. That the songs never reach for any kind of release makes them that much more effective in their creepiness, which has always been Low's strong suit anyway. At its most eerie and beautiful, Low is the sound of idealism and morality clanging against true life.